1. Field of the Invention
The invention relates to a serial interface transmission structure, and in particular to a simple and efficient serial interface transmission structure.
2. Description of Related Art
In general, a serial interface transmission structure should (1) have modest logic devices and input/output pins; (2) be capable of automatically returning to an IDLE mode; (3) be able to easily read/write data from/to devices, such as in-circuit emulators (ICEs), to which are connected thereto; and (4) be able to continuously poll the status messages of the devices. A conventional serial interface "Tap Controller" described in IEEE 1149.1 (JTAG) could be considered a regular serial interface. However, the transmission structure of the conventional serial interface "Tap Controller" totally defines 16 modes, wherein the conventional serial interface must have at least 4 input/output pins. Since the conventional serial interface requires more hardware sources and its transmission structure has as many as 16 modes, this results in the disadvantages of difficult operation and low efficiency.